1. Technical Field of the Invention
This invention relates to radio telecommunication systems and, more particularly, to a system and method of providing data services in an Internet Protocol (IP)-based Global System for Mobile Communications (GSM) radio telecommunications network.
2. Description of Related Art
In GSM networks, devices for interworking with modems and Integrated Services Digital Network (ISDN) data protocols are located in an Interworking Function (IWF) in the mobile network. The IWF may be integrated with the Mobile Switching Center/Visitor Location Register (MSC/VLR), or may be implemented in a stand-alone manner as a shared IWF. Typically, manufacturers implement a proprietary protocol for use between the IWF and mobile terminals in the network which is basically independent of the fixed network protocol.
The existing network configuration causes problems when attempting to implement GSM data services in Internet Protocol (IP)-based GSM networks. First, in IP-based GSM networks, the payload is not routed through the MSC/VLR; therefore, a traditional implementation of the IWF in the MSC/VLR cannot be utilized. Second, the payload is transported over IP; therefore, even if the IWF is implemented as a stand-alone shared IWF, a GSM-standard (circuit switched) IWF cannot be utilized. The protocols in GSM between the IWF and the mobile station are standardized, but they are separate from the fixed network protocol. Third, the modems and ISDN data protocols are located in a Signaling System 7 (SS7) gateway; however, existing SS7 gateways do not support GSM radio protocols.
There are no known prior art teachings of a solution to the aforementioned deficiencies and shortcomings such as that disclosed herein. It would be advantageous to have a system and method of handling GSM data services in IP-based GSM networks which overcomes the disadvantages of existing solutions. The present invention provides such a system and method.
In one aspect, the present invention is a method of providing data services in an Internet Protocol (IP)-based radio telecommunications network. The method includes implementing an Internet Protocol Shared Interworking Function (IP-SIWF) in the radio telecommunications network, and controlling the IP-SIWF from a Mobile Switching Center (MSC) utilizing a device control protocol. When a data call carrying a data payload is originated by a mobile terminal, the data call is transported utilizing radio access and radio link protocols to the IP-SIWF. The radio access and radio link protocols are terminated in the IP-SIWF, and the data payload is transported thereafter utilizing a real time protocol (RTP) over a User Datagram Protocol (UDP) and an IP protocol layer.
In another aspect, the present invention is an IP-based radio telecommunications network for providing data services to a mobile terminal. The network includes an MSC serving the mobile terminal, and means for originating a data call carrying a data payload from the mobile terminal utilizing radio access and radio link protocols. An IP-SIWF is connected to the MSC by signaling links and is controlled by the MSC utilizing a device control protocol. The IP-SIWF includes means for terminating the radio access and radio link protocols and transporting the data payload thereafter utilizing a real time protocol over a UDP and an IP protocol layer. The network may also include a Media Gateway and means within the IP-SIWF for sending the data payload to the Media Gateway utilizing a media gateway protocol.